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5eePRELIMINARY EVALUATION PART ONE: TEAR FILM EVALUATION AND CORNEAL TOPOGRAPHY

5eePRELIMINARY EVALUATION PART ONE: TEAR FILM EVALUATION AND CORNEAL TOPOGRAPHY. DRY EYE SYMPTOMS (Nichols et al, 2005). N = 893 52% of CL wearers reported dry eyes 24% of spectacle wearers 7% of clinical emmetropes. TEAR FILM EVALUATION. Role of Tear Film Lipid Layer Aqueous Layer

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5eePRELIMINARY EVALUATION PART ONE: TEAR FILM EVALUATION AND CORNEAL TOPOGRAPHY

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  1. 5eePRELIMINARY EVALUATION PART ONE: TEAR FILM EVALUATION AND CORNEAL TOPOGRAPHY

  2. DRY EYE SYMPTOMS (Nichols et al, 2005) • N = 893 • 52% of CL wearers reported dry eyes • 24% of spectacle wearers • 7% of clinical emmetropes

  3. TEAR FILM EVALUATION • Role of Tear Film • Lipid Layer • Aqueous Layer • Mucin (Mucous) Layer

  4. LIPID LAYER • Thin anterior surface of tear film • Secreted by Meibomian Glands and Glands of Zeiss and Moll • Functions to retard evaporation of the tear film between blinks and promotes tear film stability

  5. AQUEOUS LAYER • Thick, central section of tear film • Reflexly secreted by the lacrimal gland and basally by the glands of Wolfring & Krause • Functions include the lubrication of the corneal surface, high optical quality and maintains an neutral pH

  6. MUCIN (MUCOUS) LAYER • Thin mucoid layer located adjacent to the cornea • Formed by the goblet cells of the conjunctiva • It is abundant in glycoproteins

  7. MUCIN LAYER FUNCTIONS • Decreases surface tension of the tear film and minimizes dry spot formation • Minimizes hydrophobic effects contributed by the lipid layer and serves as the mechanism by which lipids and other metabolic wastes are removed from the tear film with the blink

  8. ROLE OF TEAR FILM IN BLINKING • Complete blinking action vital for a stable tear film • If absent or improper, dry eye results • During the blink, the overlying aqueous tear film completely wets the mucin-coated epithelium • Between blinks, the tear film thins via evaporation and exits into the fornices; thus lipid layer comes closer to mucin layer.

  9. ROLE OF TEAR FILM IN BLINKING • When proximity is such that mucin layer is contaminated by lipid layer, dry spots occur • Therefore, mucin layer is essential for maintaining the continuity of the tear film • These problems are avoided in individuals with normal tear film stability and volume as well as having a complete uninterrupted blink

  10. “JELLYBUMPS”

  11. TEAR FILM ABNORMALITIES/DEFICIENCIES • Aqueous (volume) Deficiency • Mucin Deficiency • Lipid Deficiency • Lid Surfacing Abnormalities • Tear Base Abnormalities

  12. AQUEOUS (VOLUME) DEFICIENCY • Associated with decrease in aqueous production of accessory & lacrimal glands • K Sicca and Sjogren’s Syndrome are associated this • Aqueous production decreases via use of antianxiety, antihistamine, anticholinergic & oral contraceptives • Manage via artificial tears; punctal plugs

  13. MILD AQUEOUS DEFICIENCY • Can continue with CL wear • Use artificial tears (i.e., Refresh Contacts); if > qid: use preservative-free such as Refresh Plus (Allergan), BionTears (Alcon) or TheraTears (Advanced Vision Research)

  14. Moderate Aqueous Deficiency • Definite reduced Tear BUT; use higher viscosity tears such as: Refresh Liquigel (Allergan), GenTeal Gel (Novartis) • Systane (Alcon) highly recommended as is proven to increase BUT; changes from a liquid to a gel moments after instillation

  15. Severe Dry Eye • Cl wear is variable; depends upon effectiveness of treatment • Need therapeutic agents: • 1) 0.05% Restasis (cyclosporine) bid (wait 10 minutes prior to CL use); may take 4 weeks to have an effect . . . Sometimes up to 12 weeks • 2) “soft” steroid (Lotemax or loteprednol 0.5%): may try initially for a few weeks; if relief then an inflammatory component is present; then go to restasis or taper Lotemax

  16. MUCIN DEFICIENCY • Decrease in mucin production from a decrease in conjunctival goblet cells; results in an unstable tear film and low tear BUT • Associated with an absence of Vitamin A • Associated with ocular pemphigoid, Stevens-Johnson Syndrome • Contact lenses are contraindicated

  17. LIPID DEFICIENCY • Greasy tear film present due to Meibomian gland infection resulting in dry spot formation • Close association exists between blepharitis, abnormal Meibomian gland function and dry eye • Management via proper patient education, lid hygiene

  18. LIPID DEFICIENCY • If lid hygiene is not totally successfully, supplement with: • 1) Lipid replacement drops: Soothe (Alimera Sciences) or Refresh Endura (Allergan) • 2) Omega-3 fatty acids

  19. LID SURFACING ABNORMALITIES • If patient is partial blinker or incomplete closure, inferior SPK can result from improper blinking • Drying also caused by entropion/ectropion

  20. TEAR BASE ABNORMALITIES • Problems such as recurrent erosion, filamentary keratitis and persistent epithelial defects can result in dryness • Management via bandage lenses and lubricants to decrease discomfort and allow re-epithelialization

  21. METHODS OF EVALUATION • Tear Break-Up Time • Phenol Red Cotton Thread (Zone-Quick) • Schirmer • Rose Bengal • Biomicroscope • Laboratory Tests

  22. TEAR BREAK-UP-TIME (BUT) • Most widely used test of lacrimal function • Best predictor of contact lens success • Length of time for dry spots to develop as the mucin layer is contaminated by lipids • Decreases with age and high ambient temperature • After fluorescein instillation, use wide beam and low magnification • Avg = 12.8sec.; 15% < 10 sec.

  23. TEAR BREAK-UP-TIME • Do not manipulate lids • Do not use BAK preserved solutions • Several blinks before measuring • No tonometry prior to test • Use yellow filter over observation system • Repeat test several times • 6 - 10 secs = borderline; ≤ 5 secs: do not fit

  24. PHENOL RED COTTON THREAD • Developed in Japan and used on several hundred thousand patients • Consists of 70mm cotton thread soaked in phenol red dye • Now known as Zone-Quick from Allergan/Menicon • Performed similar to Schirmer; placed in temporal third of lower lid for 15 sec.; measure the red portion in mm

  25. PHENOL RED COTTON THREAD • Avg. = 16.7mm; <9mm = dry eye • Benefits: no anesthesia & minimal discomfort; 15 second test time; little reflex secretion; more valid than Schirmer • Criticisms: relatively low absorption capacity; may only measure residual tears in cul-de-sac, not tear volume

  26. THE PHENOL RED THREAD TEST: A CROSS-CULTURAL STUDY • R Sakamoto; E Bennett, V Henry, et al Dec. 1993 Invest Ophthalmol

  27. CROSS CULTURAL STUDY • Purpose was to evaluate PRTT on Japanese and US subjects to determine norms and differences • 500 US & 500 Japanese subjects • 40 from age 0 - 9 • 160 from 10 - 19 to 60+

  28. CROSS CULTURAL STUDY • US Mean = 23.9mm (ranged from 32 to 20.9) • Japan Mean = 18.8mm (ranged from 24.9 to 18.8)

  29. SHORT TERM EFFECT OF ANTIHISTAMINES ON THE TEAR FILM: PART ONE EVALUATION OF TEAR FILM SENSITIVITY • J Morrison, R Hart, E Bennett, L Naeger, et al

  30. SHORT TERM EFFECT OF ANTIHISTAMINE USE • N = 12 non CL Wearers • Mean age - 23 • 3 one week phases; subject given either: • Two 60 mg Seldane/fructose • Three 25mg Benedryl • Three fructose • Drugs taken days 1 - 3 only

  31. SHORT TERM EFFECTS OF ANTIHISTAMINE USE • Results showed: • PRTT most sensitive • Not significantly different from Tear BUT

  32. SCHIRMER TEAR TEST • Evaluates basal tear secretion and part of reflex secretion • Strip of paper 5 x 30mm placed slightly temporal over lower lid with upward gaze • Low room illumination • Avg = 22.3mm for normals; 7.6mm for dry eye patients • >10mm (5min.) & >6mm (1 min.) =normal

  33. SCHIRMER TEAR TEST: CRITICISMS • Anesthetic Use • Inconsistent • Uncomfortable

  34. ROSE BENGAL • Stains dead and degenerated epithelial cells • Beneficial in diagnosis of K sicca • Typically, inferior staining is present

  35. BIOMICROSCOPY • Tear Meniscus • Evaluation of height and quality of lower tear prism; if not continuous, aqueous deficiency present • Where meniscus meets cornea, a black line exists that represents localized thinning; observed with fluorescein and cobalt blue filter

  36. KEELER Tearscope Plus • Evaluates shape of tear meniscus to determine to determine quantity • Assess quality via matching tear film pattern with a commonly used grading system • $1390UK

  37. BIOMICROSCOPY • Interference Phenomena: • Spectrum of colored interference patterns of lipid layer will be observed with patient viewing superiorly • Specular reflection in combination with high intensity illumination and high magnification should be used • If lipid layer is insufficient, no interference patterns will be observed

  38. LABORATORY TESTS • Lacrimal Protein Concentration • 1. Lysozyme agar diffusion test • 2. Lactoplate lactoferrin immunological test system Tear Film Osmolality: increase in TFO results from insufficient tear film turnover and evaporation These procedures are diagnostic of dry eye but are expensive and time-consuming

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